The present invention relates to medical devices. More particularly, the invention relates to an intravascular filter which has a distal filter basket which allows blood to flow through, but captures emboli, the filter device having a flexible arm having magnetic characteristics and which serves as a component of an alarm which allows a physician to know whether the filter has become filled or clogged by emboli or other debris.
Filtering devices are percutaneously placed in body vessels of a variety of medical patients, including but not limited to trauma patients, orthopedic surgery patients, neurosurgery patients, or in patients having medical conditions requiring bed rest or non-movement. During such medical conditions, the need for filtering devices arises due to the likelihood of thrombosis in the peripheral vasculature of patients wherein thrombi break away from the vessel wall, risking downstream embolism or embolization. For example, patients in danger of suffering strokes may have a filter placed in each of the left and the right carotid arteries, potentially in the common portion of the carotid arteries, as many strokes are caused by emboli originating from the carotid bifurcation.
Typically, the filtering devices are permanent implants, each of which remains implanted in the patient for life. However, it can be desirable to remove or empty implants when they fill. In the case of a carotid artery filter, a clogged or filled filter can result in reduced blood flow to the brain. Because filters can fill gradually, it is advantageous to have a way of monitoring the status of each filter regularly and noninvasively. However, large thromboemboli can also break off and cause rapid filling of the filter as well.
Implanted medical devices which incorporate an element which can generate a signal that can be detected by a device which is outside of the body, or that can modulate a signal that is originates outside the body. The detector may be small and portable, and which produces minimal or no radiation will be helpful in better monitoring the status of a patient's condition.
It is desirable to include a built-in way of monitoring blood flow through a filter, which correlates to the amount of embolic material trapped in the filter, so that timely intervention can be made in a patient in need thereof.